This is a UV-AR coated, UV double-convex lens, model number 49-251, available from Edmund Optics. The lens has a diameter of 9mm and a focal length of 18mm, making it a compact yet powerful optical component. The base shape is circular, and the lens is spherical, featuring both front and back surfaces curved outwards (convex-convex).
The lens's geometry includes a thickness of 1.32mm at the edge and 2.6mm at the center. The effective focal length (EFL) is 18mm, and the back focal length (BFL) is 17.09mm. The first radius of curvature (R1) is 16.09mm, and the second radius of curvature (R2) is -16.09mm, indicating a converging lens. The inner and outer radii are both 0, suggesting a uniform curvature.
The lens is made from fused silica material, identified as fused sil mal-1965 in the item data. This material is known for its high transparency in the ultraviolet (UV) region, making this lens suitable for UV applications. The lens is coated with a UV-AR coating, providing anti-reflective properties in the UV range of 250-425nm. This coating enhances the lens's performance by reducing unwanted reflections and increasing transmission.